The present study determined effects of saliva and/or Lipoteichoic acids (LTA) on the in vitro colonization of surfaces by a variety of serotypes of S. mutans. In experiments which measured the growth and sucrose-mediated adherence of S. mutans to glass surfaces, human, monkey and rat saliva caused a pronounced inhibition of adherence of serotype b (rat type) cells and little or no effect on the adherence of serotype c and g (human type) cells. The most pronounced differences on sucrose-mediated adherence were related to the serotype strains tested and not to the type of saliva in the assay. Serotype b strains in contrast to serotype c and g strains synthesize large amounts of LTA. Results of in vitro adherence assays suggest that the large amounts of LTA associated with serotype b (BHT) cells could decrease their ability to adhere to preexisting dental plaque which contrains LTA; adherence of serotype c (Ingbritt) or serotype g (OMZ-65) cells would not be affected.